1. Field of the Invention
This invention pertains to food processing, and more particularly to apparatus that molds individual patties from a bulk quantity of a food product.
2. Description of the Prior Art
Various equipment has been developed to make individual food patties on a high production basis. For example, it is well known to load a quantity of ground meat, such as beef or pork, into a hopper of a molding machine. The meat is forced from the hopper through a pump box and into a manifold. From the manifold, the ground meat flows through fill slots into multiple cavities in a mold plate. The mold plate with the filled cavities advances in a longitudinal direction to a knockout station, at which the meat is pushed out of the cavities. The mold plate then returns to a fill station for refilling the cavities. U.S. Pat. Nos. 3,486,186; 3,887,964; 3,952,478; 4,054,967; 4,097,961; 4,182,003; 4,334,339; 4,343,068; 4,356,595; 4,372,008; 4,535,505; 4,597,135; 4,608,731; 4,622,717; 4,697,308; 4,768,941; 4,780,931; 4,821,376; 4,996,743; 5,021,025; 5,022,888; 5,655,436; and 5,980,228 are representative of prior machinery for making round patties from bulk quantities of ground meat. U.S. Pat. No. 4,818,446 illustrates a machine for making generally rectangular patties.
In the machines of all the aforementioned patents, the mold plate cavities are arranged in a single row that is transverse to the directions of mold plate reciprocation. Thus, for each cycle a number of patties is produced that is equal to the number of cavities in the mold plate.
To increase the production rate of producing the patties, it was necessary that the prior mold plates reciprocate faster. However, there was a practical limit as to how fast the prior machines could operate. The limitations were based on the acceleration forces produced on the reciprocating components, and also on the ability of the meat product to flow from the manifold through the fill slots into the mold plate cavities. For most prior machines, the practical limit was approximately 90 cycles per minute. If that production rate was insufficient, it was necessary for the processing plant to acquire more machines.
U.S. Pat. No. 4,975,039 describes a food molding machine having a mold plate with two transverse rows of cavities. A knockout station is between two fill stations. While one row of the mold plate cavities is being filled at a first fill station, the second row is at the knockout station. The mold plate reciprocates to bring the first row to the knockout station and the second row to the second fill station. The machine of the U.S. Pat. No. 4,975,039 is able to produce twice as many patties per cycle as machines with only one row of cavities. However, an attendant disadvantage is the cost and complexity of a machine having two separated fill stations.
U.S. Pat. No. 4,872,241 teaches a patty molding machine having a mold plate with two transverse rows of cavities. The cavities are elongated for handling a whole muscle meat product rather than a ground meat product. The cavities are staggered in the longitudinal direction to make the two rows. No cavity in either row is aligned longitudinally with any other cavity. Each cavity has its own individual fill slot. All the cavities are filled simultaneously at the fill station.
U.S. Pat. No. 4,338,702 depicts a mold plate with two rows of cavities. The cavities in one of the rows are used only as passages between the manifold and plug-forming cavities on the opposite side of the mold plate as the manifold. Only the cavities in the other row receive meat product for making patties, and only the patties in that row of cavities are knocked out at the knockout station.
In spite of the numerous designs of patty producing machines available, there is room for further developments to them.
In accordance with the present invention, a double row molding apparatus is provided that greatly increases the productivity of food patty machines. This is accomplished by apparatus that includes a mold plate having pairs of longitudinally aligned cavities and a knockout mechanism that ejects food product from all the cavities simultaneously.
Each pair of mold plate cavities has a front cavity and a back cavity. The front cavities of the pairs are aligned in a front transverse row, and the back cavities of the pairs are aligned in a back transverse row.
The mold plate has a top surface that is in flat facing contact with a breather plate. A bottom surface of the mold plate is in flat facing contact with a top plate and with a filler plate that is installed into the top plate. A drive mechanism reciprocates the mold plate in longitudinal directions between a retracted position and an extended position. At the retracted position, the mold plate cavities are between the breather plate and the filler plate. Food product is forced from a manifold through fill slots in the filler plate into the mold plate cavities. At the extended position, the cavities overhang the breather plate and the top plate, and the cavities are open at both top and bottom surfaces of the mold plate. The knockout mechanism ejects food patties from all the cavities simultaneously. The mold plate then retracts back to the retracted position for refilling the cavities, and the cycle continues. Thus, for each cycle, twice as many patties are produced as was possible using the prior machines that had a single row of cavities.
According to one aspect of the invention, there is a single long fill slot in the filler plate. The row of front cavities is in communication with the fill slot, but the back cavities are not in communication with the fill slot when the mold plate is at its retracted position. Rather, the row of back cavities are sealed from the fill slot by the close fit of the mold plate top and bottom surfaces with the breather plate and the top plate, respectively. Preferably, the fill slot is closer to the trailing edges of the mold plate front cavities than to the leading edges of the cavities. Food product is forced from the manifold through the fill slot only to the front cavities when the mold plate is at its retracted position.
The mold plate then advances toward its extended position. After only a short advancement, the front mold plate cavities lose communication with the fill slot. On the other hand, the advancing mold plate causes the back cavities to pass over the fill slot. As the back cavities pass over the fill slot, the food product, under pressure, flows through the fill slot into the back cavities. The flow of the food product into the back cavities completely fills them, which may have been partially filled previously, as will be explained shortly. When the mold plate is at its extended position, the back cavities have completely passed the fill slot, and the fill slot is sealed off from all the cavities. The knockout mechanism operates to eject the food product simultaneously from all the cavities.
During the mold plate return stroke, the back cavities again pass over the fill slot. Any residual pressure on the food product in the manifold will cause the food product to flow through the fill slot into the back cavities and partially fill them. At the end of the return stroke, when the mold plate is again at its retracted position, the front cavities are again over the fill slot, and the back cavities are sealed off from the fill slot. The mold plate dwells momentarily at the retracted position, during which time the front cavities are filled. The mold plate then advances forward. As they pass over the fill slot, the back cavities are completely filled, and the cycle repeats. It is thus seen that the back cavities fill with the food product during both forward and return strokes, but not during the mold plate dwell at the end of the return stroke. On the other hand, the front cavities fill only during the dwell at the end of the return stroke and not during either the forward or return strokes. Rather than one long fill slot that communicates with all the mold plate cavities, the filler plate may have a multiple short fill slots each associated with a respective pair of front and back cavities.
In another embodiment of the invention, there are single long front and back fill slots. The front fill slot communicates with the row of front mold plate cavities when the mold plate is at its retracted position, and the back fill port communicates with the row of back cavities. The front fill slot may be close to the trailing edges of the mold plate front cavities, and the back fill slot may be close to the leading edges of the back cavities. During the dwell of the mold plate at the retracted position, food product flows from the manifold through the two fill slots into all the cavities simultaneously. During the forward stroke of the mold plate, the front cavities quickly lose communication with the front fill slot. On the other hand, the back cavities of the mold plate pass over and temporarily communicate with the front fill slot. Any residual pressure of the food product tends to force it through the front fill slot into the back mold plate cavities. Consequently, the back mold plate cavities are fillable from both the back and front fill slots. When the mold plate has advanced to its extended position, the knockout mechanism ejects the food patties from all the cavities simultaneously.
During the mold plate return stroke, the back cavities pass over the front fill slot. Any residual pressure on the food product causes it to flow through the front fill slot into the back cavities. The back cavities can thus be partially filled during the mold plate return stroke. When the mold plate has returned to its retracted position, it dwells there momentarily while the food product flows through the front and back fill slots into the front and back cavities, respectively. Because the front cavities fill only during the dwell time, whereas the back cavities fill both during the dwell time and during the forward and return strokes of the mold plate, the front fill slot preferably has a larger cross-sectional area than the back fill slot.
If desired, the front fill slot that communicates with all the front cavities can be several short fill slots each in communication with a respective front cavity when the mold plate is at its retracted position. Similarly, several short back fill slots can be used instead of one long back fill slot.
To eject the food patties from the mold plate, the knockout mechanism of the invention has two rows of knockout cups on a single knockout bar. The knockout bar is attached to a pair of knockout slides that are guided for vertical reciprocation in respective guides. Each of a pair of knockout arms has a first end that engages a respective knockout slide. Each knockout arm is pivotally connected between its ends to a housing that is part of the double row molding apparatus. Inside the housing is a shaft with a pair of cams. The cams are in contact with second ends of the knockout arms. The shaft and cams rotate in timed relation to the reciprocation of the mold plate. For all positions of the mold plate except its extended position, the cams hold the knockout cups against a spring force away from the mold plate. When the mold plate is at its extended position, the cams allow the spring force to reciprocate the knockout cups to eject all the patties from the mold plate simultaneously.
The method and apparatus of the invention, using double rows of longitudinally aligned cavities in a mold plate, thus improves productivity of a meat patty machine. The probability of producing imperfect patties is remote, even though the back cavities are fillable on both forward and return strokes of the mold plate.
Other advantages, benefits, and features of the present invention will become apparent to those skilled in the art upon reading the detailed description of the invention.